WASHINGTON — In January 2011, newly elected Sen. Jerry Moran of Kansas joined three other Republicans in launching the Senate Tea Party caucus, dedicated to cutting government spending and reducing the federal debt.

That hasn't stopped Moran from spending more from his congressional office budget than any other senator in fiscal 2012, according to Senate financial records. Moran had spent all but $18,000 of his almost $3 million annual office budget through Sept. 30, the end of the fiscal year. The numbers are not final because late bills for all senators could arrive for up to two years.

Moran spends that much because he has to travel back and forth to Kansas to meet his constituents, his spokeswoman, Garrette Silverman, explained in an e-mail.

"Sen. Moran's commitment to staying connected with Kansans is second-to-none," Silverman says. "Much of his resources have been dedicated to flying back to Kansas from Capitol Hill virtually every weekend to have conversations with Kansans and listen to their concerns. In fact, he has held 1,000 town halls and visited hundreds of communities. His staff also dedicates their time to traveling the state, attending more than 1,000 events and meetings, and personally serving the 2.8 million Kansans Sen. Moran represents."

Senate spending data bear this out — Moran's travel budget for the year is among the top 10 in the Senate.

Senate office budgets are determined by a formula that includes a state's total number of residents and its distance from Washington, so Moran spent the highest percentage of his budget but not the most money. California Democrats Dianne Feinstein and Barbara Boxer each spent more than $4.3 million in 2012 out of an office budget of just less than $4.7 million.

Seven of the 10 senators who had spent most of their budgets by Sept. 30 are Democrats. Mark Begich of Alaska had about $60,000 left in his budget of just more than $3 million, records show. Travel costs were a major factor, says Amy Miller, spokeswoman for the first-term Democrat.

"We are not over budget and won't be over budget," Miller says. "It is the senator's belief that while in office he should do everything he possibly can to help Alaskans resolve issues involving the federal government. Case work is a high priority for our office, and we hire as many talented people as we can with the resources available to ensure Alaskans get the help they need."

High travel costs between Washington and Alaska and inside Alaska itself is expensive, she says. "Most travel has to be done by air, and it can cost $1,000 or more to travel between two communities in state."

Begich's late father, Nick, was a U.S. representative. He died in a 1973 plane crash while flying a small plane to a political event in Alaska with then-House Majority Leader Hale Boggs.

Eight out of 10 senators with the most money left over — both in actual dollars and percentage — at the end of the fiscal year were Republicans. Alabama's Richard Shelby spent about 60% of his $3 million budget and had more than $1.1 million left at the end of the fiscal year. Democrat Daniel Akaka of Hawaii had more than $800,000 left of his $2.2 million budget, making him the second most frugal.

Shelby's low expense rate is "a conscious decision to spend only what is absolutely necessary to staff the senator and serve the constituents," spokesman Jonathan Graffeo says. Shelby maintains a robust constituent service operation in the state, Graffeo says, and holds a town hall in every county every year.

Shelby also has the Senate's lowest payroll, which is each office's primary expenditure. Shelby's year-end payroll expense was a little more than $1.6 million. Only freshman Sen. Dean Heller, R-Nev., joined Shelby in having an office payroll below $2 million. Boxer spent just more than $4 million on staff, and Moran and Begich each spent about $2.7 million.

Some senators, such as Kentucky Republican Rand Paul, a founding member of the Tea Party caucus and one of the five most frugal senators in fiscal year 2012, take pride in their parsimony. In January, Paul held a news conference announcing that he had returned to the U.S. Treasury $500,000 of unspent funds from his office account from the prior year.

"I ran to stop the reckless spending," Paul said at the time. "I hope this sets an example for the rest of government — at all levels. We can carry out our duties in a fiscally responsible way. Government can be both smart and efficient. We are proving that — and trying to convince the rest of Washington."

Senate accounting practices make it hard to know how much of that money actually goes back to the taxpayer.

The Senate this year set aside funding to cover slightly less than 95% of the estimated annual budget for each senator with the expectation that most will spend less than their allocation. If senators spend less than 95% of their budgets, it appears they are leaving money in the pool to offset the costs of senators who spend more than that amount.

The secretary of the Senate holds any leftover money for two years to pay off late bills, then returns the remainder to the Treasury.

"Not spending their full budget is a personal and political decision; it is symbolic," says Brad Fitch, president of the Congressional Management Foundation, which conducts management training for congressional offices. "The taxpayers of Kansas or New York were given this amount of money, and you are acting as their steward and should spend it wisely."

Coming in way under budget, Fitch says, must be offset against the "value to constituents of hiring another caseworker to help with problems they have with the federal government."